We are studying the effects of prolonged extracorporeal circulation with a non-occlusive pump and the spiral coil silicone membrane lung on acute respiratory failure in sheep and baboons. Particular efforts are being made to understand the hemodynamics and oxygen delivery of various routes of perfusion. Hematologic effects such as platelet destruction and sequestration are being evaluated and appropriate drug modification of platelet function investigated. Modification of the basic polymers of membrane lungs in collaboration with industry is being attempted to decrease platelet destruction. We are evaluating several models of animal acute respiratory failure to allow study of their interaction with prolonged extracorporeal perfusion.